1. Field of the Invention
The present invention relates to an inductor and a method of producing such an inductor, and more particularly, the present invention relates to an inductor having a conductor (internal conductor) functioning as an inductance element that is located within a magnetic material produced by kneading a magnetic powder and a resin, and a method of producing the inductor.
2. Description of the Related Art
As shown in FIG. 7, a surface-mount inductor including a magnetic material compact body 53 that is produced by molding a magnetic material 51 obtained by kneading a magnetic powder and a resin into a mold in which a coil (internal conductor) 52 functioning as an inductance element is buried in the magnetic material 51, with both ends 52a and 52b of the coil 52 exposed at both end surfaces of the magnetic material compact body 53, and a pair of external electrodes 54a and 54b provided at both end surfaces of the magnetic material compact body 53.
This inductor can be produced by molding the magnetic material 51 obtained by kneading a magnetic powder and a resin to produce the magnetic material compact body 53, and then providing the external electrodes 54a and 54b on the magnetic material compact body 53. Thus, the step of firing the inductor at high temperature is not necessary, which is required for conventional ceramic inductors including magnetic ceramic material. Therefore, the manufacturing cost of producing the inductor is decreased.
However, in forming the external electrodes of the above-described inductor by a method including the steps of coating conductive paste and baking it, like in ceramic inductors, the resin that constitutes the magnetic material compact body decomposes in response to the heat applied during baking of the conductive paste. Under actual conditions, it is very difficult to apply the conventional method using conductive paste without modification.
Therefore, a conventional inductor is shown in FIG. 8, in which metal caps 55a and 55b are mounted as external electrodes to both ends of the magnetic material compact body so as to be connected to both ends of the coil 52. However, the metal caps are expensive and require the step of mounting the metal caps, thereby increasing production cost.
In other conceivable methods of forming the external electrodes using conductive paste, special conductive paste that can be baked at low temperature is used, or a resin having excellent heat resistance is used as the resin that constitutes the magnetic material compact body. However, both of these methods are problematic because they produce inductors with diminished and inferior properties, and decrease the ease and degree of freedom of the manufacturing process.